1.  less than Technical Field greater than 
The present invention relates to a vehicle AC generator or an alternative current generator for a vehicle and in particularly to a ventilation cooling fan of an alternative current generator for vehicle and a manufacturing method of the same.
2.  less than Prior Art greater than 
FIG. 9 is a cross-sectional view showing a construction of an alternative current generator for vehicle according to the prior art. A rotor 1 is constituted by a bobbin 3 to which a field coil 4 is wound, a yoke 5 for forming a magnetic iron core, a pair of cores 2 comprised of plural claw shape configuration portion chips (plates), a front fan 15 and a rear fan 14 which are welded and fixed to an end face of the core 2, a rotating shaft 6, and a slip ring 7. The pair of cores 2 sandwiches the bobbin 3 to which the field coil 4 is wound and the yoke 5 and claws 2a are arranged to mesh, and the cores 2 are inserted and fixed to a substantial center portion of the rotating shaft 6.
To an outer peripheral portion of the rotor 1 a stator 8 is arranged and to surround the stator 8 a front bracket 10 and a rear bracket 11 are installed. To one of the end portions of rotating shaft 6, a pulley 12 is installed and a rotational force of an engine not shown in figure is transmitted to the pulley 12 through a belt not shown in figure and the rotor 1 is rotated and driven. In accordance with the rotation of the rotor 1, the front fan 15 and the rear fan 16 which are installed to the core 2 rotate together and an inner portion of the generator is ventilation-cooled.
As shown in FIG. 9, the front side bracket 10 has plural intake holes 22 and the plural exhaust holes 23 and also the rear side bracket 11 has plural intake holes 22 and the plural exhaust holes 23, respectively, and in the rotation of the rotor 1 an interior portion of the alternative current generator is ventilation-cooled using the front fan 15 and the rear fan 16.
FIG. 10 is a perspective view showing a fan which is employed in the alternative current generator for vehicle according to the prior art. A conventional fan 16 is transformed from one sheet thin plate using a press working, and the structure of the fan 16 is that plural curved face (or a flat face) blades 17 are provided projectingly in an axial direction according to the transforming by a ring shape supporting plate 18 and by bending a part of the ring shape supporting plate 18. As a result, a sheet number of the blades 17 and a height of the blades 17 have a relative relationship, therefore a freedom degree in a fan design receives a restriction.
Recently, a high speed drive of an alternative current generator for vehicle comes into wide use in accordance with a high output performance request for the alternative current generator for vehicle. As the high speed drive advances, there causes a problem in which the noises of the alternative current generator for vehicle increase. Many of the noises during the high speed drive time are wind noises accompanying with the rotation of a rotor, in particular the affects by the turbulence flow noises according to the rotation of a cooling fan and the interference noises occupy a large element.
For this reason, the noise increase has restrained by an alternation of the sheet number of the blades of the cooling fan, an alternation of a curvature radius of the blades, an employment of back ward blades, and an employment of an irregular pitch arrangement of the blades. However, the silence noise performance at the vehicle side (an engine except for the alternative current generator, auxiliary machineries, etc.) is advanced, a correspondence to the low noise performance by the alternation of the shape configuration by a thin plate press transforming fan according to the prior art reaches to the limitation.
In the thin plate press transforming fan according to the prior art, since one sheet iron plate is punched out using a die and transformed by bending the iron plate, it receives many restrictions on the design relating to the sheet number of the blades, the height of the blades, and the arrangement of the blades, etc.
An object of the present invention is to obtain an alternative current generator for a vehicle wherein a fan structure in which a freedom degree on a shape configuration design can be made high, an installation strength similar to that of the thin plate transforming fan according to the prior art can be obtained, further an alternation in a fan installation process can not be generated.
According to the present invention, in an alternative current generator for a vehicle comprising a pair of cores having plural claw shape portion configuration plates, a rotating shaft inserted into a center portion of the core, a rotor inserted and fixed to the rotating shaft and having an excitation current supply use slip ring, a stator provided at an outer periphery of the rotor, and a front side bracket and a rear side bracket arranged to surround the rotor and the stator, the rotor is supported to rotate freely each of the brackets through a bearing member, the core is comprised of a pair of a front fan and a rear fan which are installed to both ends of said core, to end portions of the respective front side and rear side brackets plural intake holes are provided, and an outer peripheral portion of respective front side an rear side brackets plural exhaust holes are provided, and in accordance with a rotation of the rotor an inner portion of the generator is ventilation-cooled using the front and rear fans.
The alternative current generator for the vehicle is characterized in that at least one of the front fan and the rear fan is a resin molding fan having an insert metal fitting, and a fixing of the resin molding fan to the core is carried out by joining the insert metal fitting to the core by using a joining means such as a welding.
According to the invention, since the structure of the cooling fan is formed by the resin molding product having the insert metal fitting, the blade shape configuration can be realized by the curved face, the flat face and also the three dimensional shape configuration, and further a ring shape rectifying plate can be provided in the tip end side of the blade. Further, according to the employment of the resin molding fan, the sheet number of the blades and the suitable pitch of the blades can be established freely within a realizable degree.
Further, in the resin molding fan itself, it is difficult to obtain the full installation strength during the joining time to a back face of the core, however, in the resin molding fan having the insert metal fitting, in accordance with the insert metal fitting since the mechanical connection can be carried out by the welding etc. to the back face of the core, it is possible to ensure the installation strength similar to that of the press transforming product using the thin plate according to the prior art.
According to the invention, since the inner diameter of the ring shape supporting plate in which the blades of the cooling fan are projectingly provided is established to have substantially same diameter of the outer diameter of the rotating shaft of the rotor or the outer diameter of the slip ring which is inserted and fixed to the rotating shaft, the positioning of the axial center against the core of the cooling fan during the installation time of the cooling fan to the back face of the core can be carried out easily.
According to the invention, since to the rear face (the contact face with the core) of the ring shape supporting plate in which the blades of the cooling fan are projectingly provided, the raised portion which is suited to the root portion of the core is provided, as a result the positioning of the cooling fan against to the rotation direction of the core can be carried out easily.